Drug testing

Drug testing is used to determine whether a person has consumed various psychoactive substances. It is used by the sports industry and is often used by employers. It is also widely used in the criminal justice system, and in the federal system, is mandatory for federal probationers, where failed drug tests are one of the leading causes of probation violations. Failed urine screens are sometimes verified through more expensive procedures such as mass spectroscopy and gas chromatography. Another relatively expensive drug testing method is hair testing. [Who says?]